not getting the output from ATMega8

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//there are 5 adc ports in atmega8( PC0 to PC5)
//I am using PC1,PC2 and PC4 for connecting the LDR sensors
 
 
 
 
 
 
 
#include <avr/io.h> 
#include<util/delay.h>
int a[3];    //Array to store the sensor voltages 
int main(void) 
{ 
  DDRC=0b0000000;       //Set port A to input 
  DDRB=0b00011110;   //Set port B to output 
 
   
    while(1) 
    { 
    ADMUX=0b00101000; 
    int i; 
    for(i=1;i<5;i++)    //Read values of the inputs //      PC1-centre,PC 2-left, PC4-right
    {   
      ADCSRA=0b00011111; 
      while(ADCSRA&(1<<ADSC)); 
      ADMUX++; 
      a[i]=ADCH;  //Values stored in ADCH transferred to the array 
    } 
         
        if(a[2]>a[4] && a[2]>a[1])   //left sensor highest 
       PORTB=0b00000010;  //Turn left 
       
  else 
  if(a[4]<a[1] && a[1]>a[2])    //Centre sensor highest 
      PORTB=0b00010010;  //Go straight 
       
  else 
  if(a[4]==a[1])  //Any two sensors getting same value, then go straight 
      PORTB=0b00010010;  
       
  else 
  if(a[1]==a[2]) 
      PORTB=0b00010010;  
       
  else 
  if(a[4]>a[1] && a[4]>a[2])      //Right sensor highest 
     PORTB=0b00010000;     //Turn right 
     
    } 
return 0; 
}